1. Field of the Invention
The present invention relates to devices used to measure the flow of a liquid, or flow meters. More particularly, the present invention relates to flow meters having a tangentially oriented rotor and a compact and relatively simple design.
2. Background of the Invention
Flow meters of various design are known in the art for measuring fluid flow. In general, flow meters are designed with an internal rotor that rotates as fluid or, more specifically, liquid passes through the meter. The turbine rotates at a rate that is related to the rate of fluid flow and a sensing mechanism in the meter measures the rotation. This measurement may then be used directly or further processed to produce an indication of the rate of fluid flow through the meter.
Examples of flow meters are found in U.S. Pat. No. 4,885,943 (Tootell), U.S. Pat. No. 4,825,708 (Sevick), U.S. Pat. No. 4,872,352 (Alden), and U.S. Pat. No. 4,140,013 (Hunger). A drawback of the systems shown in these patents is that the flow meter is housed separately from the signal processing electronics, thus requiring two distinct components that must be interconnected by a signal cable.
U.S. Pat. No. 4,848,164 (Quarve) describes a flow meter system that includes both a flow detection component and signal processing electronics. A drawback of that system is that the rotor cannot be observed by the user, and the flow meter is composed of three housing units that must be disassembled in order to gain access to the rotor. The use of separate housing units also increases the risk of external fluids and/or gases seeping into the meter through the junctures of the units.
Another drawback of conventional flow meters is their inability to provide an accurate measure of the flow rate. In particular, many flow meters will indicate a flow rate when, in fact, no fluid is flowing ("a no flow environment.")
Therefore, it is an object of the present invention to provide a flow meter that includes both the sensing mechanism and the signal conditioning circuitry in a compact single housing unit. A further object is to provide a flow meter with signal conditioning circuitry that may be directly connected to an analog processor without the need for external conditioning circuitry. Another object is to provide a unitary flow meter that allows manual access to the turbine or rotor without having to remove the sensing mechanism or the electronic circuitry from the unit. Yet another object is to provide a flow meter with a high level of durability and which is highly accurate in providing fluid flow data.